Operation principles of bidirectional isolated AC/DC converter with natural clamping soft switching scheme

The bidirectional isolated AC/DC converter is widely used in the past decades. Most of the topologies are based on voltage source converter. However, the performance of the voltage source based converter is significantly limited by the bulky energy storage element, the range of soft switching, the leakage inductance of the transformer and so forth. A current fed isolated AC/DC converter is studied in the paper. A novel soft switching control scheme is used in this topology, which could achieve the natural clamping and the zero current commutating. Instead of causing the voltage spike problem, the leakage inductance of the transformer could be utilized to assist the soft switching. The natural voltage clamping and the soft switching could be achieved without limiting the operating range of the inductor into discontinuous current mode. The control scheme and PWM generation scheme is analyzed in this paper. Simulation results are used to validate the operation of the novel control scheme in this topology.